The present invention relates to a method for discriminating a tire class, that is discriminating a tire type based on a train of symbols installed in the side of the tire.
A class recognition label for classifying tire type is attached on manufactured tires. Namely a coded numeral, a character, or numeral concavely shaped is attached on the tire, and many methods and apparatus for automatically decoding a recognition label of class attached on the tire have been proposed.
For example, a method for discriminating a tire type comprising of micro projections corresponding to signal indicates a tire type in which the tire bead hill portion is the best in dimension and is the best plane surface among the portions of the tire along the circumference of the tire, and detecting projections by contact or noncontact manner; converting the detected signal to a digital signal; then discriminating tire type by comparing the digital signal with a predetermined signal corresponding to the tire type, is proposed in the Japanese patent publication sho 55-83965.
Also, a method for discriminating tire type with the following method that forms a discriminating bar concave or convex shape at the side wall of the tire radially along its circumferential direction, wherein said discriminating bar provides regularity per tire type, then scans with a sensor at the prominence and depression of the discriminating bar and detects, is proposed in the Japanese patent. publication sho 58-72439.
Moreover, a method for automatically discriminating tire type comprising: a step detecting with detecting arm a position of the mark portion pre-provided at some position having certain relation to a train of symbols that is composed of the character or numeral installed concave or convex shaped in the side wall of tire; a step positioning at a readable position of train of symbols by directly moving a read arm of the character or numeral etc. with the moving read arm based on the output signal from position detecting arm; a step the reading the character or numeral of train of symbols by read arm; a step discriminating the character, or numeral of train of symbols by discriminating the arm based on the output signal from the read arm, is proposed in the Japanese patent publication sho 61-43382.
This forms a character or numeral indicating discrimination of the tire with an inversed V shape, thereby clearing contrast against the background of a character or numeral, while it uses an one dimensional image sensor as read unit and performs a scan by scanning signal with fixed frequency, and inputs a two-division one dimensional image signal in that the background region is black and symbol region is white as a buffer, and provides conclusively a two dimensional image signal. To discriminate said two dimensional image signal is to judge the tire class.
Thus, it is possible to use dot code as a train of symbols indicating a class of the tire. Also, a unit for reading automatically a dot code, for example unit for decoding dot code document, photographic optically colored region with dot code and discriminating between convexed dot and concaved dot based on the photographic image data, thereby converts dot code to KANA(Japanese alphabet), is disclosed in the Japanese patent publication hei 7-234632.
However, if dust is attached to a position where a dot does not initially exist, the dust is recognized as a dot. Subsequently, because of decoding into a wrong character, that results in erroneous discrimination.